I've found some SoC's:
JN516x needs BeyondStudio IDE, which is available only on Windows.
JN517x seems to be developed not for mass market since no online shops sell them.
BTW, these MCUs were originally developed by Jennic and has 32-bit RISC architecture.
KW21Z (KW41Z) has Cortex M0+ core, and needs less current. IDE is crossplatform eclipse-based MCUXpresso.
And I know that Xiaomi uses JN5169 in theis sensors and hub, as long as Aqara, but not KW21Z.
Which MCU is the best to start development?